Elevated plasma vasopressin (AVP) levels during resection of pheochromocytomas

During the evaluation of epidural blockade with light general anesthesia for pheochromocytoma resection, increases in plasma arginine vasopressin (AVP) concentrations were noted. We measured AVP levels in conjunction with plasma catecholamines during perioperative maneuvers in eight consecutive patients undergoing resection of pheochromocytomas. Hormonal responses (mean +/- SE) for preoperative baseline and peak values during tumor manipulation were as follows: AVP, 5 microgram/ml or picogram/ml (+/- 1.7) to a peak of 129 pg/ml (+/- 44) pg/ml; norepinephrine, 5,834 pg/ml (+/- 2,564) to 72,422 (+/- 31,433) pg/ml; epinephrine, 1,033 pg/ml (+/- 405) to 56,444 (+/- 23,542) pg/ml; and dopamine, 165 pg/ml (+/- 35) to 4,231 (+/- 1,318) pg/ml. Maximal AVP values occurred with tumor manipulation and remained elevated for 24 hours postoperatively. Neither epidural placement, induction of anesthesia, nor epidural narcotics used for postoperative pain control had any effect on AVP or catecholamine levels. These extraordinarily high concentrations of plasma AVP found during tumor manipulation may contribute to hemodynamic lability and fluid problems in patients undergoing surgery for the treatment of pheochromocytoma.